Good Luck: Nonagonal
Last but not least is the nonagonal good luck knot. More accurately Greek vs Latin, the term enneagonon is more "correct", but nonagon is the more popular and commonly used term. Plus there's this whole ennegram/enneagram personality thing to confuse matters. Best to stick with nonagon, am I right?!? 8)
Note: I have an undergrad degree in Math and Computer Science, plus dad was a Math professor for many decades, but I'm no authority or specialist in geometry by any stretch of the imagination. This is a pop-sci level of analysis and at any time a real mathematician could step in and tell us I'm entirely wrong. 8) I hope not. Not that I don't welcome real mathematicians (I can't even tell you how long I looked for the term "star polygon" which I just knew had to exist...) but I'm just hoping I'm not too far wrong. 8)
So, to make this knot I used a paper template. If I was carrying around my hole puncher like I sometimes do, I could have made a 9 holed template, but all I had was my scissors (and some paper), so with a casual folding attitude, I made a 12 holed template. Picked 9 of the biggest holes (sometimes folds that were on an inner layer don't get cut as well as the outer layers) to pull my loops through and crowned away. Similarly, my heptagonal good luck knot was constructed using a template with 8 holes. I used an overlap of 3 for this knot and the structural centre is visibly much thicker than the previous knots.
Ah, I feel much better now and I was going to stop at this point unless you want me to keep going. Should we see how many overlaps we need until the structural centre goes spherical? 8)